While visiting Argrathi, Chief of Operations Miles O'Brien asks too many questions and is convicted of espionage. Instead of incarcerating convicts, the Argrathi correctional facility implants them with memories of years of imprisonment in a few hours of actual time. O'Brien experiences twenty years in prison before his fellow officers can extract him from the situation.
On returning to Deep Space Nine, O'Brien tries to adjust back to life on board the station, but his experiences while imprisoned still trouble him, presenting as flashbacks to his time in jail. Seeing his wife Keiko initially as his fictional cellmate Ee'char, he begins to exhibit habitual behaviours that he "picked up" while "incarcerated," such as hoarding food and sleeping on the hard floor instead of his bed.
While playing darts with Commander Worf, O'Brien sees Ee'char outside the bar, but when he tries to follow him outside, Ee'char is nowhere to be seen. Over time, O'Brien becomes increasingly irritable and reclusive. While waiting to be served at Quark's bar, he assaults Quark; immediately, across the table, O'Brien sees Ee'char, who tells O'Brien he needs him. Quark and Constable Odo are seen observing O'Brien from across the bar.
Captain Sisko later relieves O'Brien of duty, placing him on medical leave and ordering him to attend the counselling sessions that he'd been consistently avoiding. O'Brien storms into Doctor Bashir's infirmary, angry at being placed on leave and telling Bashir that he just wants to be left alone. Again, he imagines seeing Ee'char, who urges him to get help, but instead he storms out and returns to his quarters. Keiko and their young daughter Molly are there, and O'Brien yells at them before almost hitting Molly. He flees to a cargo bay and starts tearing the place apart. Finding a weapons locker, he sets a phaser on maximum, preparing to take his own life.
Bashir follows O'Brien and finds him just in time. O'Brien recounts the story of how he'd killed Ee'char over a few pieces of bread and that the guilt has been eating away at his conscience. Bashir ultimately prescribes a new course of heavy treatment and soon has O'Brien on the way to recovery.